Effects of Irradiation and Blast on Pulmonary Function in Sheep

The changes in pulmonary function that result following unilateral exposure to LD50 doses of neutron-gamma irradiation and/or sublethal blast overpressures were investigated in sheep. Animals exposed to blast-only and radiation-plus-blast demonstrated large increments in venous admixture on the day of insult followed by a major recovery toward baseline values during the first 24 hours following injury. The venous admixture of the blast-only animals approached baseline 7 days after exposure but that of the radiation-plus-blast sheep did not return to baseline until 21 days. The sheep exposed to radiation-only, blast-only, and radiation-plus-blast sustained similar reduction in means carbon monoxide diffusing capacity (DLCO) which were below that of the control mean at 2 days and 7 days post exposure. All of the radiation-only and radiation-plus-blast sheep that survived to or beyond 21 days displayed an overshoot or recovery to their individual baseline DLCO values. The blast-only and radiation-plus-blast animals also exhibited an increased mean ineffective alveolar ventilation (VAIneff) which persisted from 1 to 14 days following the onset of trauma. The radiation-only sheep had an increased VAIneff from 2 through 7 days post exposure. (Author)